This invention relates to the control of sediment. The term “sediment” is used herein to denote solid particulate material, e.g. soil, sand or pebbles, which can become suspended, or which is suspended, in a flowing stream of liquid, and which will settle out of the liquid when the liquid ceases to flow. The term “sediment control roll” is used herein to denote an article which can be transported and placed (i) on top of a substrate, usually the ground, in order to collect sediment from a sediment-bearing stream of liquid, usually water, which passes through the sediment control roll, or (ii) around an existing land mass composed of, for example, soil, sand, pebbles or rocks, in order to prevent or reduce removal of sediment from the land mass by water flowing towards, along, over or through the land mass. The term “land mass” is used herein to include, but is not limited to, a slope, a gully, a beach, or the bank of a body of water, e.g. a river or lake.
It is often desirable, and sometimes legally required, to collect sediment from liquid in which it is suspended, or to stabilize an existing mass of sediment to prevent it from being carried away. For example, in some cases, the law requires removal of sediment from liquid flowing out of a construction site. Often, there is neither time nor space to collect suspended sediment merely by placing the sediment-bearing liquid in a pond and allowing the sediment to settle. The conventional method for collecting sediment is to place hay bales or wattles across the path of the liquid. More recent methods are described in, for example, U.S. Pat. Nos. 6,422,787, 6,547,493 and 6,641,335, the disclosures of which are incorporated herein by reference. These known methods make use of large masses of water-absorbent materials which are secured to each other and/or held together by binders. The water-absorbent materials retain sediment and absorb large quantities of water until they are saturated. This makes them heavy, so that they are difficult or impossible to reuse and/or recycle. In many cases, they are left in place to form part of the landscape.